1. Field of the Invention
The present invention relates to a fluid-filled vibration damping device which exhibits a vibration damping effect based on flows of a non-compressible fluid enclosed therein, and which is particularly suitable for use as, e.g., automotive-vehicle engine mounts, body mounts, and differential mounts.
2. Related Art Statement
There is known a fluid-filled vibration damping device as a sort of vibration damping connecting or supporting device that is interposed between constituent members of a vibration transmitting system. The fluid-filled vibration damping device includes a first mounting member; a second mounting member including a tubular portion having an end open toward the first mounting member, the first and second mounting members being spaced from, and opposed to, each other; and an elastic rubber body which elastically connects the first and second mounting members to each other, and which fluid-tightly closes the open end of the tubular portion of the second mounting member and cooperates with the tubular portion to define a fluid chamber filled with a non-compressible fluid. When a vibrational load is applied to the vibration damping device, it exhibits a vibration damping effect based on flows of the fluid in the fluid chamber, in particular, resonance of the fluid.
Meanwhile, there has been proposed another fluid-filled vibration damping device which includes, in addition to the above-indicated members, a working or umbrella-shaped member which is supported by the first mounting member such that the umbrella member extends, in the fluid chamber, in a direction substantially perpendicular to a central axis of the tubular portion of the second mounting member, and thereby divides the fluid chamber into two divided chambers which are located on opposite sides of the umbrella member, respectively, and which are communicated with each other via a fluid-flow restricting passage defined by at least the umbrella member.
To the second fluid-filled vibration damping device including the umbrella member, a main vibrational load is applied in a direction in which the first and second mounting members are opposed to each other, i.e., a direction parallel to the central axis of the tubular portion of the second mounting member. Upon application of the main vibrational load to the vibration damping device, the umbrella member is reciprocatively moved in the fluid chamber, so that the fluid flows through the fluid-flow restricting passage. The vibration damping device can exhibit a vibration damping effect based on the flows of the fluid through the restricting passage, in particular, the resonance of the fluid.
However, even in the second fluid-filled vibration damping device, the vibration damping effect based on the flows of the fluid through the restricting passage defined by the umbrella member is not satisfactory yet and, in some cases, the vibration damping device cannot exhibit a low dynamic spring effect to a desirable degree.